Plastic containers, used for filling with juices, sauces etc., often are hot filled and then cooled to room temperature or below for distribution to sell. During the process of hot filling and quenching, the container is subjected to different thermal and pressure scenarios that can cause deformation, which may make the container non-functional or visually unappealing. Typically, functional improvements are added to the container design to accommodate the different thermal effects and pressures (positive and negative) that can control, reduce or eliminate unwanted deformation, making the package both visually appealing and functional for downstream situations. Functional improvements can include typical industry standard items such as vacuum panels and bottle bases to achieve the desired results. However, it is often desirable that these functional improvements, such as vacuum panels, are minimal or hidden to achieve a specific shape, look or feel that is more appealing to the consumer. Additional requirements may also include the ability to make the container lighter in weight but maintain an equivalent level of functionality and performance through the entire hot fill and distribution process.
Existing or current technologies such as vacuum panels in the sidewall of the container may be unappealing from a look and feel perspective. Vacuum panels rely on different components to function efficiently and effectively. One of the components of the efficiency includes the area in which the deformation to internal positive or negative pressure is controlled and/or hidden. Technologies that include a vacuum panel in the base portion thus are restricted by surface area of the container. Because of this, the shape and surface geometry that define the bottle's appearance, along with the potential to make the bottle lighter, such as reducing material used, must be considered. In addition to surface area, another factor in the performance of a vacuum panel can be its thickness distribution. That is, material thickness can play a role in how the panel responds to both positive and negative internal pressure. Through surface geometry however, the effect of material distribution can be addressed to provide a functional panel that performs consistently as it is intended within a desired process window. For example, with the continued development of lighter weight containers with reduced sidewall thickness, it may be necessary to provide a surface geometry capable of controlled deformation at lower pressure differentials. Thus there is a continued need to develop a base with surface geometries that utilize the limited base area to address the inconsistencies that are presented during the blow process specific to material distribution and the varying dynamics the container will be exposed to through the product lifecycle, as well as to expand the limits of the containers shape and/or weight while maintaining the functionality needed to perform as intended.
Furthermore, an additional factor for consideration in designing a container for use in a hot-fill application is the rate of cooling. For example, a hot-fill container filled at 180° F. generally may need to be cooled to at least about 90° F. in about 12-16 minutes for commercial applications. Therefore, a need exists for a container that can accommodate different rates of cooling. Preferably, such a container is capable of accommodating both negative pressures relative to the atmosphere due to such cooling as well as positive pressures due to changes in altitude or the like, internal pressure exerted during the hot-fill and capping process, as well as flexing to retain overall bottle integrity and shape during the cooling process.